Clot retrieval device for removing clot from a blood vessel

ABSTRACT

A clot retrieval device is disclosed to remove clot from a blood vessel. The device can include a collapsed configuration and an expanded configuration. The device can include an inner expandable body with a framework of struts. The device can include an outer expandable body with a framework of struts that at least partially radially surrounding the inner expandable body. A distal portion of the outer expandable body can extend in the deployed configuration towards the outer expandable body to a greater extent than the inner expandable body, closed cells of the distal portion distally tapering and being smaller than cells proximal thereof in the outer expandable body. The plurality of closed cells of the distal portion can include a pair of axially aligned smaller diamond shaped cells formed by struts of the distal portion and positioned along upper and lower regions of the distal portion.

FIELD

The present disclosure generally relates to devices and methods forremoving blockages from blood vessels during intravascular medicaltreatments.

BACKGROUND

Clot retrieval devices are used in mechanical thrombectomy forendovascular intervention, often in cases where patients are sufferingfrom conditions such as acute ischemic stroke (AIS), myocardialinfarction (MI), and pulmonary embolism (PE). Acute obstructions mayinclude clot, misplaced devices, migrated devices, large emboli and thelike. Thromboembolism occurs when part or all of a thrombus breaks awayfrom the blood vessel wall. This clot (now called an embolus) is thencarried in the direction of blood flow. An ischemic stroke may result ifthe clot lodges in the cerebral vasculature. A pulmonary embolism mayresult if the clot originates in the venous system or in the right sideof the heart and lodges in a pulmonary artery or branch thereof. Clotsmay also develop and block vessels locally without being released in theform of an embolus—this mechanism is common in the formation of coronaryblockages. There are significant challenges associated with designingclot removal devices that can deliver high levels of performance. First,there are a number of access challenges that make it difficult todeliver devices. In cases where access involves navigating the aorticarch (such as coronary or cerebral blockages) the configuration of thearch in some patients makes it difficult to position a guide catheter.These difficult arch configurations are classified as either type 2 ortype 3 aortic arches with type 3 arches presenting the most difficulty.

The tortuosity challenge is even more severe in the arteries approachingthe brain. For example it is not unusual at the distal end of theinternal carotid artery that the device will have to navigate a vesselsegment with a 180° bend, a 90° bend and a 360° bend in quick successionover a few centimetres of vessel. In the case of pulmonary embolisms,access is through the venous system and then through the right atriumand ventricle of the heart. The right ventricular outflow tract andpulmonary arteries are delicate vessels that can easily be damaged byinflexible or high profile devices. For these reasons it is desirablethat the clot retrieval device be compatible with as low profile andflexible a guide catheter as possible.

Second, the vasculature in the area in which the clot may be lodged isoften fragile and delicate. For example neurovascular vessels are morefragile than similarly sized vessels in other parts of the body and arein a soft tissue bed. Excessive tensile forces applied on these vesselscould result in perforations and hemorrhage. Pulmonary vessels arelarger than those of the cerebral vasculature, but are also delicate innature, particularly those more distal vessels.

Third, the clot may comprise any of a range of morphologies andconsistencies. Long strands of softer clot material may tend to lodge atbifurcations or trifurcations, resulting in multiple vessels beingsimultaneously occluded over significant lengths. More mature andorganized clot material is likely to be less compressible than softerfresher clot, and under the action of blood pressure it may distend thecompliant vessel in which it is lodged. Furthermore the inventors havediscovered that the properties of the clot may be significantly changedby the action of the devices interacting with it. In particular,compression of a blood clot causes dehydration of the clot and resultsin a dramatic increase in both clot stiffness and coefficient offriction.

The challenges described above need to be overcome for any devices toprovide a high level of success in removing clot and restoring flow.Existing devices do not adequately address these challenges,particularly those challenges associated with vessel trauma and clotproperties.

SUMMARY

It is an object of the present design to provide devices and methods tomeet the above-stated needs. It is therefore desirable for a clotretrieval device to remove clot from cerebral arteries in patientssuffering AIS, from coronary native or graft vessels in patientssuffering from MI, and from pulmonary arteries in patients sufferingfrom PE and from other peripheral arterial and venous vessels in whichclot is causing an occlusion.

In some examples, a clot retrieval device is disclosed to remove clotfrom a blood vessel. The device can include a collapsed configurationand an expanded configuration. The device can include an innerexpandable body with a framework of struts. The device can include anouter expandable body with a framework of struts that form closed cellslarger than the closed cells of the inner expandable body and at leastpartially radially surrounding the inner expandable body. The outerexpandable body can include a distal scaffolding zone with a pluralityof struts that distally taper with closed cells smaller than cellsproximal thereof in the outer expandable body. The plurality of closedcells of the distal scaffolding zone can include a first plurality ofclosed cells being axially aligned smaller diamond shaped cells formedby struts of the distal scaffolding zone; a second plurality of closedcells being larger than cells of the first plurality of closed cells andradially separated, each smaller diamond shaped cell being radiallyinward and distal of each of the second plurality of closed cells; and athird plurality of closed cells radially separated and proximal of eachof the second plurality of closed cells.

In some examples, the first plurality of closed cells can include adifferent shape than the second plurality of cells. The second pluralityof closed cells can include a different shape than the third pluralityof closed cells.

In some examples, the distal scaffolding zone can be a protective strutstructure can include at least twelve closed cells between the first,second, and third plurality of closed cells.

In some examples, the first plurality of closed cells can include a pairof axially aligned smaller diamond shaped cells formed by struts of thedistal portion and positioned along upper and lower regions of thedistal scaffolding zone.

In some examples, each diamond shaped cell can include a best fitdiameter of approximately 1.2 mm.

In some examples, the second plurality of closed cells can include atleast four cells.

In some examples, the at least four cells can include a best fitdiameter of approximately 1.6 mm.

In some examples, each of the at least four cells can share only onecommon edge with one of the smaller diamond shaped cells.

In some examples, each of the at least four cells can be a pentagon.

In some examples, the third plurality of radially separated cells caninclude at least five radially separated cells proximal of the secondplurality of cells.

In some examples, struts of the distal scaffolding zone are connected tothe inner expandable body.

In some examples, struts of the distal scaffolding zone form a mesh-likestructure.

In some examples, the distal scaffolding zone can include a porositygreater than a porosity provided by the plurality of struts of the outerexpandable body proximal thereof.

In some examples, a clot retrieval device is disclosed to remove clotfrom a blood vessel. The device can include a collapsed configurationand an expanded configuration. The device can include an innerexpandable body with a framework of struts. The device can include anouter expandable body with a framework of struts that at least partiallyradially surrounding the inner expandable body. A distal portion of theouter expandable body can extend in the deployed configuration towardsthe outer expandable body to a greater extent than the inner expandablebody, closed cells of the distal portion distally tapering and beingsmaller than cells proximal thereof in the outer expandable body. Theplurality of closed cells of the distal portion can include a pair ofaxially aligned smaller diamond shaped cells formed by struts of thedistal portion and positioned along upper and lower regions of thedistal portion.

In some examples, the distal portion is a protective strut structurethat can include at least twelve closed cells of the plurality of closedcells.

In some examples, the plurality of closed cells of the distal portioncan include at least four radially separated larger cells, each smallerdiamond shaped cell being radially inward and distal of the at leastfour radially separated larger cells.

In some examples, the at least four radially separated larger cells caninclude a best fit diameter of approximately 1.6 mm.

In some examples, each of the at least four radially separated largercells sharing only one common edge with one of the smaller diamondshaped cells.

In some examples, each of the at least four radially separated largercells form a pentagon.

In some examples, the plurality of closed cells of the distal portioncan include at least five radially separated cells proximal of the atleast four radially separated larger cells.

In some examples, the framework of struts of the outer expandable bodycan include a plurality of discontinuous expandable members spaced fromadjacent expandable members, struts of each expandable can form closedcells with at least some struts terminating in radially separated distalapexes free from connection to an adjacent closed cell.

In some examples, the device can include a plurality of clot inletmouths between respective expandable bodies through which clot may passand enter the device.

In some examples, each member can include at least four radiopaquemarkers equally radially separated about a longitudinal axis of theouter expandable body.

In some examples, the at least four radiopaque markers being separatedapproximately 10 mm apart in the collapsed configuration.

In some examples, the at least four radiopaque markers being separatedapproximately 8 mm apart in the expanded configuration.

In some examples, the at least four radiopaque markers radiopaquemarkers can include radiopaque material positioned in an eyelet.

In some examples, the at least four radiopaque markers radiopaquemarkers can include at least one of Barium Sulphate, BismuthSubCarbonate, Barium OxyChloride, Gold, Tungsten, Platinum, Iridium,Tantalum or an alloy of these materials.

In some examples, the device can include at least three expandablemembers longitudinally spaced apart.

In some examples, the plurality of closed cells of the distal portionforming a distal mesh; the inner expandable body can include a closeddistal portion and the distal portion of the outer expandable body beingclosed; and the distal portion of the outer and inner expandable bodiestogether configured to prevent distal egress of clot or clot fragmentsfrom the device.

In some examples, the outer expandable body being expandable to a radialextent greater than the inner expandable body to define a clot receptionspace eccentrically arranged about a longitudinal axis of the outertubular body.

In some examples, the outer expandable body can include a closed distalportion.

In some examples, a plurality of distal struts of the closed distalportion are spiraled.

In some examples, a plurality of distal struts of the closed distalportion extend normal to a longitudinal axis of the outer expandablebody.

In some examples, a plurality of distal struts of the closed distalportion are configured in a bulged or flared pattern.

In some examples, the outer and inner expandable bodies each beingmonolithic structures.

In some examples, the outer expandable body can include at least twolongitudinally spaced-apart expandable members connected by one or morestruts configured as a longitudinal hinge between the spaced-apartexpandable members, each expandable member can include a plurality ofradially separated radiopaque markers.

In some examples, each marker is positioned at a junction between atleast two connecting struts of a respective expandable member.

In some examples, each member can include at least four radiopaquemarkers equally radially separated about a longitudinal axis of theouter expandable body.

In some examples, the device can include at least three expandablemembers longitudinally spaced apart.

In some examples, the radiopaque markers can include radiopaque materialpositioned in an eyelet.

In some examples, the radiopaque markers can include at least one ofBarium Sulphate, Bismuth SubCarbonate, Barium OxyChloride, Gold,Tungsten, Platinum, Iridium, Tantalum or an alloy of these materials.

In some examples, a diameter of the flow channel in the expandedconfiguration being less than 50% of a diameter of the outer expandablebody in the expanded configuration along a longitudinally-extending clotreception space between the inner and outer expandable bodies.

In some examples, the device can include a shaft extended proximally ofa proximal end of inner and/or outer expandable bodies.

In some examples, the device can include struts of the distal portionbeing connected to the inner expandable body.

Other aspects and features of the present disclosure will becomeapparent to those of ordinary skill in the art, upon reviewing thefollowing detailed description in conjunction with the accompanyingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further aspects of this disclosure are further discussedwith the following description of the accompanying drawings, in whichlike numerals indicate like structural elements and features in variousfigures. The drawings are not necessarily to scale, emphasis insteadbeing placed upon illustrating principles of the disclosure. The figuresdepict one or more implementations of the inventive devices, by way ofexample only, not by way of limitation. It is expected that those ofskill in the art can conceive of and combining elements from multiplefigures to better suit the needs of the user.

FIG. 1 shows an isometric view of a clot retrieval device of thisdisclosure.

FIG. 2 shows an isometric view of another example of a clot retrievaldevice of this disclosure.

FIG. 3 shows a side view of the device of FIG. 1.

FIG. 4A shows a side plan view of the outer member of the clot retrievaldevice of FIGS. 1-2.

FIG. 4B shows a top plan view of the outer member of the clot retrievaldevice of FIGS. 1-2.

FIG. 5 shows a close-up view of section A-A of FIG. 1.

FIG. 6 shows a close-up view of section B-B of FIG. 3.

FIG. 7 shows a close-up view of section C-C of FIG. 3.

FIG. 8 shows a close-up view of section D-D of FIG. 3.

FIG. 9 shows a close-up isometric view of a distal region of the exampleclot retrieval device of FIG. 1.

FIG. 10A shows an end view of the distal region of FIG. 9.

FIG. 10B shows an isometric view of the distal region of FIG. 9.

FIG. 10C shows a top view of the distal region of FIG. 9.

FIG. 11A shows a close-up isometric view of an example marker.

FIG. 11B shows a side plan view of the example marker of FIG. 11A.

FIG. 12 shows a close-up of on expandable member of an example outermember in a collapsed configuration showing example laser cut patterns.

DETAILED DESCRIPTION

Specific examples of the present disclosure are now described in detailwith reference to the Figures, where identical reference numbersindicate elements which are functionally similar or identical. Theexamples address many of the deficiencies associated with traditionalcatheters, such as inefficient clot removal and inaccurate deployment ofcatheters to a target site.

Accessing the various vessels within the vascular, whether they arecoronary, pulmonary, or cerebral, involves well-known procedural stepsand the use of a number of conventional, commercially-availableaccessory products. These products, such as angiographic materials andguidewires are widely used in laboratory and medical procedures. Whenthese products are employed in conjunction with the system and methodsof this disclosure in the description below, their function and exactconstitution are not described in detail.

The following detailed description is merely exemplary in nature and isnot intended to limit the disclosure or the application and uses of thedisclosure. Although the description of the disclosure is in many casesin the context of treatment of intracranial arteries, the disclosure mayalso be used in other body passageways as previously described.

It will be apparent from the foregoing description that, whileparticular embodiments of the present disclosure have been illustratedand described, various modifications can be made without departing fromthe spirit and scope of the disclosure. For example, while theembodiments described herein refer to particular features, thedisclosure includes embodiments having different combinations offeatures. The disclosure also includes embodiments that do not includeall of the specific features described. Specific embodiments of thepresent disclosure are now described in detail with reference to thefigures, wherein identical reference numbers indicate identical orfunctionality similar elements. The terms “distal” or “proximal” areused in the following description with respect to a position ordirection relative to the treating physician. “Distal” or “distally” area position distant from or in a direction away from the physician.“Proximal” or “proximally” or “proximate” are a position near or in adirection toward the physician.

Accessing cerebral, coronary and pulmonary vessels involves the use of anumber of commercially available products and conventional proceduralsteps. Access products such as guidewires, guide catheters, angiographiccatheters and microcatheters are described elsewhere and are regularlyused in cath lab procedures. It is assumed in the descriptions belowthat these products and methods are employed in conjunction with thedevice and methods of this disclosure and do not need to be described indetail. The following detailed description is merely exemplary in natureand is not intended to limit the disclosure or the application and usesof the disclosure. Although the description of the disclosure is in manycases in the context of treatment of intracranial arteries, thedisclosure may also be used in other body passageways as previouslydescribed. A common theme across many of the disclosed designs is a duallayer construction in which the device includes an outer expandablemember within which runs an inner expandable member, both members beingdirectly or indirectly connected to an elongate shaft, and a distal netor scaffold configured at the distal end of the device to prevent theescape of clot fragments. This distal net may be appended to either theshaft, the inner or the outer members or to several of these. A range ofdesigns are envisaged for each of these elements as described throughoutthis document, and it is intended that any of these elements could beused in conjunction with any other element, although to avoid repetitionthey are not shown in every possible combination.

For example both the inner and outer expandable members are desirablymade from a material capable of recovering its shape automatically oncereleased from a highly strained delivery configuration. A superelasticmaterial such as Nitinol or an alloy of similar properties isparticularly suitable. The material could be in many forms such as wireor strip or sheet or tube. A particularly suitable manufacturing processis to laser cut a Nitinol tube and then heat set and electropolish theresultant structure to create a framework of struts and connectingelements. This framework can be any of a huge range of shapes asdisclosed herein and may be rendered visible under fluoroscopy throughthe addition of alloying elements (e.g., Platinum) or through a varietyof other coatings or marker bands. The inner expandable member may insome cases form a generally tubular structure and is ideally configuredto expand to a lesser diameter than that of the smallest vessel in whichit is intended to be used. This diameter is typically less than 50% thatof the outer expandable member may be as low as 20% or less of the outermember diameter. A range of different distal scaffolding zone designsare disclosed, some of which incorporate strut elements from theframework of the outer and/or inner expandable members, and some ofwhich incorporate fine wires or fibers to provide added scaffolding withminimal impact of overall device profile or deliverability. Suitablematerials ideally have a high tensile strength so that a very fine wireor fiber with sufficient integrity for manufacturability and use can beproduced, such as for example polymers materials such as UHMWPE, Aramid,LCP, PET or PEN, or metals such as Tungsten, MP35N, stainless steel orNitinol.

FIG. 1 shows one embodiment of a clot retrieval device 100 with an outerexpandable member 102 and an inner expandable member 103 to facilitaterestoration of blood flow through clot immediately after device 100 isdeployed at an obstructive site. As shown, member 102 can include four(4) expandable members proximal of the distal portion. However, anynumber of expandable members are contemplated. For example, FIG. 2 showsa modified device 100′ with fewer expandable member sections (e.g., two(2) as shown) of member 102. FIG. 3 shows a side of device 100 butwithout the proximal shaft. Device 100 has an elongate shaft 106 havinga distal end that extends interior of the artery and a proximal end thatextends exterior of the artery. Members 102 and 103 have a collapsedconfiguration for delivery and an expanded configuration for clotretrieval, flow restoration and fragmentation protection. Member 103 canhave a generally tubular body section.

Member 103 is configured to self-expand upon release from a restrainingsheath (e.g., a microcatheter) to a diameter larger than that of member102. Expansion of member 102 can cause compression and/or displacementof the clot during expansion. When an expandable body provides a highlevel of scaffolding, the clot is compressed. When an expandable bodyprovides an escape path or opening the expanding body will urge the clottowards the opening. However if the expandable body provides only modestscaffolding the clot will be displaced but since the clot has manydegrees of freedom it may move in a variety of different directions andtherefore cannot be controlled. By providing a tubular expandable bodywhere the length of the tubular expandable body is substantially as longas the length of the occlusive clot or longer, many of the degrees ofmovement freedom available to the clot are removed.

Members 102 and 103 can specifically have a collapsed configuration fordelivery and an expanded configuration for flow restoration andfragmentation protection. Members 102, 103 can be joined at the proximaland distal ends during assembly to minimize tension within members 102,103 during use. In other examples, member 103 may not be connected tothe distal end of member 103 at all or may be constrained within member102 without being fixedly attached. In other examples, member 103 canhave a non-cylindrical cross-section, may be non-uniform in diameter,and may have tailored strut patterns to provide regions of differingradial force or flexibility. The length of member 102 can besubstantially the same as the length of member 103 in the freelyexpanded configuration and the loaded, collapsed configuration.

Member 103 can have an elastic or super-elastic or shape-memory metallicstructure and can have a polished surface such as an electro-polishedsurface. Member 103 can be configured so as to provide a flow lumen orflow channel (e.g., generally cylindrical section) through device 100 tofacilitate restoration of blood flow past the clot upon deployment. Inone embodiment, member 103 is configured to scaffold the flow channelthrough the clot to prevent the liberation of fragments which mightotherwise lodge in the distal vasculature. Member 103 can include one ormore connected struts 131 configured to contact a clot when initiallydeployed in a target vessel within the clot. The contact of the one ormore struts 131 with the clot provides additional grip and assists inthe initial dislodgement of the clot from the vessel when device 100 isretracted.

The distal end of member 103 can include an expansile section formedfrom expanded struts 110 which have a diameter greater than that ofmember 103. These expanded struts 110 can be connected to a coil section118 (see, e.g., FIG. 8) that can be laser cut from the tubing thatmember 103 can also be cut from. Coil 118 can also be configured toaccommodate minor length differentials by stretching without applyingsignificant tensile or compressive forces to device 100. Coil 118 can beformed from a stainless-steel material, a polymer or from a moreradiopaque metal such as gold or platinum or an alloy of such amaterial. Coil 118 can be replaced with a longitudinal length of anelastic material such as a low modulus polymer or elastomer. The distalend of the coil 118 can be joined to the distal collar 109 of member 102(e.g., by adhesive, a solder, weld or braze process). In some examples,struts 110 can elongate during loading so that the lengths of themembers 102, 103 can be equal when fully loaded in a microcatheter.Length differentials between members 102, 103 can still occur whendevice 100 is deployed in a small vessel or during the loading ordeployment process.

Members 102 and 103 are preferably made of a super-elastic orpseudo-elastic material such as Nitinol or another such alloy with ahigh recoverable strain. Shaft 106 may be a tapered wire shaft, and maybe made of stainless steel, MP35N, Nitinol or other material of asuitably high modulus and tensile strength. Shaft 106 may have indicatorbands 107 to indicate when the distal end of device 100 is approachingthe end of the microcatheter during insertion. Shaft 106 can have a coil104 adjacent its distal end and proximal of members 102, 103. Coil 104may be metallic and may be formed from stainless steel or from a moreradiopaque material such as platinum or gold for example or an alloy ofsuch a material. In other examples, coil 104 can be coated with a lowfriction material or have a polymeric jacket positioned on the outersurface of the coil 104. Adjacent to coil 104 a sleeve 105 may bepositioned on shaft 106. Sleeve 105 may be polymeric and may bepositioned over a tapered section of shaft 106. Sleeve 105 may berendered radiopaque through the addition of a filler material such astungsten or barium sulphate. However, other radiopaque materials arecontemplated, including but not limited to Bismuth SubCarbonate, BariumOxyChloride, Gold, Platinum, Iridium, Tantalum or an alloy of any ofthese materials. The sleeve 105 and shaft 106 may be coated with amaterial to reduce friction and thrombogenicity. The coating may includea polymer, a low friction lubricant such as silicon, a hydrophilic or ahydrophobic coating. This coating may also be applied to the member 102and member 103.

FIG. 4A shows a side plan view of member 102 while FIG. 4B shows a topplan view of member 102. Inlet openings 122 are provided in member 102whereby inlets 122 can provide a primary movement freedom available tothe clot and so the expansion of member 102 urges the clot intoreception space 111. Member 102 can have multiple inlet mouths 122 toaccept clot. Inlet mouths 122 can be configured to allow portions of theclot to enter reception space 111 and thus allow the clot to beretrieved without being excessively compressed. This is advantageousbecause the inventors have discovered that compression of clot causes itto dehydrate, which in turn increases the frictional properties of theclot, and increases its stiffness, all of which makes the clot moredifficult to disengage and remove from the vessel. This compression canbe avoided if the clot migrates inward through the wall of member 102 asthe porous structure migrates outward towards the vessel wall.

The inlet mouths 122 can also provide the added benefit of allowingmember 102 when retracted to apply a force to the clot in a directionsubstantially parallel to the direction in which the clot is to bepulled from the vessel (i.e. substantially parallel to the central axisof the vessel). This means that the outward radial force applied to thevasculature may be kept to a minimum, which in turn means that theaction of the clot retrieval device 100 on the clot does not serve toincrease the force required to dislodge the clot from the vessel, thusprotecting delicate cerebral vessels from harmful radial and tensileforces.

Member 102, as shown, can include proximal struts 120 connected at theirproximal ends to collar 112 and at their distal ends to a firstexpandable member 126, which is more clearly shown in FIG. 6 at sectionB-B. As shown, struts 120 may have a tapered profile to ensure a gradualstiffness transition from shaft 106 to the clot engagement section ofthe device. Member 126 can be connected to a second expandable member127 by a plurality of connecting arms 129, which can run from a proximaljunction 139 to a distal junction 140. Arms 129 can include generallystraight struts running parallel to the central axis of the device. Inother embodiments these connecting arms may include a plurality ofstruts configured in one or more cells or may include curved or spiralarms. The region between the first and second expandable member includestwo inlet mouths 122 through which clot may pass and enter the receptionspace 111 defined by the region between the inner and outer members.

Member 127 can in turn be connected to a third expandable member 128 byconnecting arms 130, which run from a proximal junction 141 to a distaljunction 142. Arms 130 can include generally straight struts runningparallel to the central axis of device 100. In some examples, arms 130can include a plurality of struts configured in one or more cells or mayinclude curved or spiral arms. The region between members 127, 128 caninclude one or more inlet mouths 122 through which clot may pass andenter the reception space 111 defined by the region between members 102,103. Arms 129 between members 126, 127 may be substantially aligned witharms 130 between members 127, 128 to align the neutral axis of members126, 127, 128 during bending. In other examples, arms 129 betweenmembers 126, 127 may be aligned at an angle, such as 90 degrees, witharms 130 between members 127, 128.

In some examples, member 126 can include interconnected struts, such aswith strut 143 terminating in crowns 133 with no distal connectingelements, and other struts such as 144 terminating in junction points145 and 146. Struts in the expandable members may be configured so thatduring loading, multiple crowns (e.g., crowns 145, 150) do not align atthe same distance from the proximal collar 112. During loading orresheathing, a higher force can be generally required to load a crownthan a strut into the sheath. Accordingly, if multiple crowns are loadedat the same time the user may notice an increase in loading force. Byoffsetting the crowns (e.g., crowns 145, 150) by making alternativestruts 144 and 151 different lengths the loading force may be reducedand the perception to the user is improved. Similarly, second expandablemember 127 can include interconnected struts, such as strut 147,terminating in crowns 134 with no distal connecting elements, and otherstruts (e.g., strut 148) terminating in junction points. Similarly,third expandable member 128 can include interconnected struts, such asstrut 152, terminating in crowns 135 with no distal connecting elements,and other struts terminating in junction points. FIG. 7 shows aclose-view of section C-C of FIG. 3 more clearly showing member 128 andits struts (e.g., strut 152) and crowns 135. As shown, fewer or greatexpandable members 126, 127, 128 may be included with member 102.

In some examples, expandable members of member 102 may include one ormore markers 125 with radiopaque materials such as, but not limited to,a radiodense material such as Gold, Tungsten, Tantalum, Platinum oralloy containing these or other high atomic number elements. Polymermaterials (e.g., polyurethane, pebax, nylon, polyethylene, or the like)might also be employed, containing a Radiopaque filler such as BariumSulphate, Bismuth SubCarbonate, Barium OxyChloride, Gold, Tungsten,Platinum, Iridium, Tantalum, an alloy of these materials, and/or anadhesive filled with radiopaque filler. In this respect, marker 125 canbe included as an eyelet on struts throughout member 102. Marker 125 canbe positioned to indicate to the user the distal end of the barrelsection of member 102 to aid in accuracy of deployment. The distal endof member 102 can include a circumferential ring of struts 123 connectedto a series of struts 124 that can terminate at a distal junction point109, which can include a collar. In some examples, member 102 canterminate in a closed distal end while in other aspects, the distal endof member 102 can be opened or not necessarily closed. In some examples,struts 124 may include a generally conical shape, as shown. In someexamples, struts 124 can be arranged in a generally flat plane which maybe inclined or may be normal to the longitudinal axis of device 100.Struts 124 and 149 can be tapered to a narrower width than those of themore proximal struts including the body of the expandable members (e.g.,members 126, 127, 128, etc) thus creating a gradual transition in thestiffness of the device both in the expanded and collapsed states.

FIG. 5 is a close-up view of section A-A of FIG. 1 more clearly showingexample markers 125 staggered on and along member 126. It is understoodthat the position of markers 125 as shown in FIG. 7 and throughout thisdisclosure are merely exemplary and markers 125 can be includedelsewhere and with other features of device 100. In some examples,markers 125 can be separated approximately 10 mm apart in the collapsed,delivery configuration and be separated approximately 8 mm apart in theexpanded configuration. However, markers 125 are not so limited and canseparated as needed or required.

FIG. 8 shows a close-up view of section D-D of FIG. 3 more clearlyshowing distal region 155 while FIG. 9 shows close-up isometric view ofa distal region 155 (sometimes referred herein interchangeably as adistal scaffolding zone) of device 100 at section E-E of FIG. 3. FIGS.10A (end view) and 10B (isometric view) show the distal region 155 ofmember 102 only where a three-dimensional distal mesh of region 155 isconfigured for fragment protection feature is created by a framework ofstruts. As shown, a plurality of apexes or crowns 184 of distal region155 shown in FIGS. 9-10C are provided connected to a plurality of arms182 proximal thereof, which terminate at a junction proximate collar109. Arms 182 can be shaped as needed or required, including generallybowed or conical as depicted. Preferably, arms 182 form a plurality ofclosed cells gradually going from larger closed cells at or adjacent theproximal end of region 155 to smaller closed cells at or adjacent thedistal end. In some examples, at least twelve closed cells can beprovided in distal region 155 of device 100. The distal region 155 showncan include a closed distal end of member 102 which, together with themesh formed by arms 182 of region 155 and corresponding closed cells,can prevent egress of clot or clot fragments that have entered thepreviously described reception space 111 between members 102,103.

In some examples, axially aligned smaller diamond shaped cells 187 canbe formed by arms 182 and positioned along upper and lower regions ofthe distal mesh. In some examples, at least two cells 187 are provided.Larger cells 189 can be positioned radially about longitudinal axis L ofdevice 100 and radially inward of cells 187. In some examples, at leastfour cells 189 are provided joined at or adjacent a junction proximatecollar 109. In some examples, cells 189 can measure approximately 1.2mm, said measurement being the size of a best fit diameter of a circleplaced in respective cell (e.g., cell 187 of shown drawn in the top viewof FIG. 10C). In other examples, cells 189 can measure larger (e.g.,approximately 1.6 mm).

Cells 186 can also be provided proximal of cells 187, 189. In someexamples, at least five (5) cells 186 radially separated about axis Lcan be positioned proximal of cells 187, 189. Each of cells 186 caninclude struts common with cells 187, 189 as well as crowns 184. In someexamples, the proximal struts of each of cells 186 can be bowed orotherwise curved. In some examples, the distal region 155 of FIGS. 9-10Cshown can be a monolithic structure integrally formed with regions ofmember 102 proximal thereof (e.g., by being laser machined from the sametube as the rest of member 102). In some examples, radiopaque coil 108(e.g., formed of platinum, gold, an alloy, etc.) can be positioneddistal of the distal region 155 configured to couple at or againstdistal collar 109.

FIG. 11A shows a close-up isometric view of an example marker 125 whileFIG. 11B shows a side plan view of marker 125. The markers 125 shown areformed generally of platinum-iridium, though as previously discussed,other radiopaque materials are contemplated as needed or required.

FIG. 12 shows a close-up of expandable member 127 in a collapsedconfiguration showing example laser cut patterns with enhancedvisibility. It is understood that other expandable members of member 102may follow the same or similar pattern. Member 12 may include three (3)eyelet cuts staggered for marker 125. In other examples, member 12 mayinclude four (4) eyelet cuts staggered for marker 125. Fewer or greatereyelet cuts can be included as needed or required to incorporate markers125. In those examples with 4 eyelet cuts, each expandable member ofmember 102 can include 4 markers 125. In this respect, if member 102were to have three expandable members, then member 102 could include atotal of at least twelve markers 125 staggered throughout. If member 102were to have four expandable members, then at least twenty markers 125could be included with member 102 staggered throughout.

The disclosure is not limited to the examples described, which can bevaried in construction and detail. The terms “distal” and “proximal” areused throughout the preceding description and are meant to refer to apositions and directions relative to a treating physician. As such,“distal” or distally” refer to a position distant to or a direction awayfrom the physician. Similarly, “proximal” or “proximally” refer to aposition near to or a direction towards the physician.

In describing examples, terminology is resorted to for the sake ofclarity. It is intended that each term contemplates its broadest meaningas understood by those skilled in the art and includes all technicalequivalents that operate in a similar manner to accomplish a similarpurpose. It is also to be understood that the mention of one or moresteps of a method does not preclude the presence of additional methodsteps or intervening method steps between those steps expresslyidentified. Steps of a method can be performed in a different order thanthose described herein without departing from the scope of the disclosedtechnology. Similarly, it is also to be understood that the mention ofone or more components in a device or system does not preclude thepresence of additional components or intervening components betweenthose components expressly identified.

As discussed herein, a “patient” or “subject” can be a human or anyanimal. It should be appreciated that an animal can be a variety of anyapplicable type, including, but not limited to, mammal, veterinariananimal, livestock animal or pet-type animal, etc. As an example, theanimal can be a laboratory animal specifically selected to have certaincharacteristics similar to a human (e.g., rat, dog, pig, monkey, or thelike).

As used herein, the terms “about” or “approximately” for any numericalvalues or ranges indicate a suitable dimensional tolerance that allowsthe part or collection of components to function for its intendedpurpose as described herein. More specifically, “about” or“approximately” may refer to the range of values ±20% of the recitedvalue, e.g. “about 90%” may refer to the range of values from 71% to99%. Ranges can be expressed herein as from “about” or “approximately”one particular value and/or to “about” or “approximately” anotherparticular value. When such a range is expressed, other exemplaryembodiments include from the one particular value and/or to the otherparticular value.

By “comprising” or “containing” or “including” is meant that at leastthe named compound, element, particle, or method step is present in thecomposition or article or method, but does not exclude the presence ofother compounds, materials, particles, method steps, even if the othersuch compounds, material, particles, method steps have the same functionas what is named.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise.

The descriptions contained herein are examples of the disclosure and arenot intended in any way to limit the scope of the disclosure. Whileparticular examples of the present disclosure are described, variousmodifications to devices and methods can be made without departing fromthe scope and spirit of the disclosure. For example, while the examplesdescribed herein refer to particular components, the disclosure includesother examples utilizing various combinations of components to achieve adescribed functionality, utilizing alternative materials to achieve adescribed functionality, combining components from the various examples,combining components from the various example with known components,etc. The disclosure contemplates substitutions of component partsillustrated herein with other well-known and commercially-availableproducts. To those having ordinary skill in the art to which thisdisclosure relates, these modifications are often apparent and areintended to be within the scope of the claims which follow.

What is claimed is:
 1. A clot retrieval device to remove clot from ablood vessel, the device comprising a collapsed configuration and anexpanded configuration and comprising: an inner expandable bodycomprising a framework of struts; and an outer expandable bodycomprising a framework of struts that form closed cells larger than theclosed cells of the inner expandable body and at least partiallyradially surrounding the inner expandable body, the outer expandablebody comprising a distal scaffolding zone comprising a plurality ofstruts that distally taper with closed cells smaller than cells proximalthereof in the outer expandable body; the plurality of closed cells ofthe distal scaffolding zone comprising: a first plurality of closedcells being axially aligned smaller diamond shaped cells formed bystruts of the distal scaffolding zone; a second plurality of closedcells being larger than cells of the first plurality of closed cells andradially separated, each smaller diamond shaped cell being radiallyinward and distal of each of the second plurality of closed cells; and athird plurality of closed cells radially separated and proximal of eachof the second plurality of closed cells.
 2. The device of claim 1, thefirst plurality of closed cells comprising a different shape than thesecond plurality of cells; and the second plurality of closed cellscomprising a different shape than the third plurality of closed cells.3. The device of claim 1, the distal scaffolding zone being a protectivestrut structure comprising at least twelve closed cells between thefirst, second, and third plurality of closed cells.
 4. The device ofclaim 1, the first plurality of closed cells being a pair of axiallyaligned smaller diamond shaped cells formed by struts of the distalportion and positioned along upper and lower regions of the distalscaffolding zone.
 5. The device of claim 4, each diamond shaped cellcomprising a best fit diameter of approximately 1.2 mm.
 6. The device ofclaim 4, the second plurality of closed cells comprising at least fourcells.
 7. The device of claim 6, the at least four cells comprising abest fit diameter of approximately 1.6 mm.
 8. The device of claim 6,each of the at least four cells sharing only one common edge with one ofthe smaller diamond shaped cells.
 9. The device of claim 6, each of theat least four cells being a pentagon.
 10. The device of claim 6, thethird plurality of radially separated cells comprising at least fiveradially separated cells proximal of the second plurality of cells. 11.A clot retrieval device to remove clot from a blood vessel, the devicecomprising a collapsed configuration and an expanded configuration, andcomprising: an inner expandable body comprising a framework of struts;and an outer expandable body comprising a framework of struts that atleast partially radially surrounding the inner expandable body; and adistal portion of the outer expandable body extending in the deployedconfiguration towards the outer expandable body to a greater extent thanthe inner expandable body, closed cells of the distal portion distallytapering and being smaller than cells proximal thereof in the outerexpandable body; the plurality of closed cells of the distal portioncomprising a pair of axially aligned smaller diamond shaped cells formedby struts of the distal portion and positioned along upper and lowerregions of the distal portion.
 12. The device of claim 11, the distalportion being a protective strut structure comprising at least twelveclosed cells of the plurality of closed cells.
 13. The device of claim11, the plurality of closed cells of the distal portion comprising atleast four radially separated larger cells, each smaller diamond shapedcell being radially inward and distal of the at least four radiallyseparated larger cells.
 14. The device of claim 13, the at least fourradially separated larger cells comprising a best fit diameter ofapproximately 1.6 mm.
 15. The device of claim 13, each of the at leastfour radially separated larger cells sharing only one common edge withone of the smaller diamond shaped cells.
 16. The device of claim 13,each of the at least four radially separated larger cells being apentagon.
 17. The device of claim 13, the plurality of closed cells ofthe distal portion comprising at least five radially separated cellsproximal of the at least four radially separated larger cells.
 18. Thedevice of claim 11, the framework of struts of the outer expandable bodycomprising a plurality of discontinuous expandable members spaced fromadjacent expandable members, struts of each expandable forming closedcells with at least some struts terminating in radially separated distalapexes free from connection to an adjacent closed cell, each membercomprising at least four radiopaque markers equally radially separatedabout a longitudinal axis of the outer expandable body.
 19. The deviceof claim 18, the at least four radiopaque markers being separatedapproximately 10 mm apart in the collapsed configuration.
 20. The deviceof claim 18, the at least four radiopaque markers radiopaque markerscomprising at least one of Barium Sulphate, Bismuth SubCarbonate, BariumOxyChloride, Gold, Tungsten, Platinum, Iridium, Tantalum or an alloy ofthese materials.